Contact lenses have been used commercially to improve vision since the 1950s. At first contact lenses were made of hard materials that were packaged in glass vials, but were uncomfortable for many patients. Later developments, gave rise to softer more comfortable lenses made of hydrophobic hydrogels and generally referred to as soft contact lenses. Due to the ease of producing these lenses, some have suggested that soft contact lenses may be used to deliver pharmaceutical agents to a patient's eyes. Currently soft contact lenses are produced on a large scale and are packaged as individual blister packages having a bowl portion and a foil top. These packages house the soft contact lens and its aqueous packaging solution. The bowl portion is made from a hydrophobic material such as polypropylene. Polypropylene is a commonly used material for contact lens packages. Polypropylene is resilient enough to withstand the sterilization steps of contact lens manufacture, and can be injection molded into a number suitable shapes and sizes. See, U.S. CPat. Nos. 4,691,820; 5,054,610; 5,337,888; 5,375,698; 5,409,104; 5,467,868; 5,515,964; 5,609,246; 5,695,049; 5,697,495; 5,704,468; 5,711,416; 5,722,536; 5,573,108; 5,823,327; 5,704,468; 5,983,608; 6,029,808; 6,044,966; and 6,401,915 for non-limiting examples of such packaging, all of which are hereby incorporated by reference in their entirety. However, the use of polypropylene in the bowl portion of a soft contact lens package can cause problems when the soft contact lens or its packaging solution contain pharmaceutical agents, particularly antihistamines such as ketotifen.
The use of ketotifen as an eye drop to treat the symptoms such as allergic conjunctivitis is known. Applicants have added ketotifen fumarate, a pharmaceutically active salt of ketotifen, to soft contact lenses and packaged those lenses in a polypropylene bowl. However, the packaging of these lenses in a polypropylene bowl causes problems. At the desired drug concentration greater than fifty percent of drug is absorbed by the polypropylene packaging material over time and removed from either or both the soft contact lens and its packaging solution. This is an undesirable condition because if the packaging material absorbs the drug, it will be difficult to determine how much of the drug is available for use by the patient. Therefore it is desirable to find materials suitable for the bowls of blister packages that minimally absorb the drugs contained in either or both the soft contact lens and its packaging solution. This need is met by the following invention.